JPS6355915B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fermenter using flocculating yeast and bacterial cells attached to a carrier such as zeodolite or vermiculite.

In this specification, regarding context,
In Figures 2 and 3, the outflow direction of the fermentation liquid, that is, the right side in each figure is referred to as the front for convenience, and the left side is referred to as the rear.

In recent years, ethanol produced from biomass by fermentation has attracted attention as an energy alternative to oil. This reaction produces ethanol and carbon dioxide gas from glucose and other sugars, as shown in the following reaction formula.

C ₆ H ₁₂ O ₆ →2C ₂ H ₅ OH + 2CO _2As is clear from the above equation, increasing the productivity of ethanol inevitably increases the rate of production of carbon dioxide gas, which causes the flocs and carriers of flocculating yeast to increase. The attached bacterial cells rose inside the tank as the generated carbon dioxide bubbles rose, and there was a tendency for them to flow out of the tank. In order to solve such problems, in conventional fermentation tanks, as shown in FIG. As shown in FIG. 2, a method was taken in which the bottomed cylindrical tank body 21 was tilted upward in the forward direction. In addition, in FIGS. 1 and 2, 14 and 24 are raw material supply pipes;
5 and 25 are fermentation liquid outflow pipes, 16 and 26 are gas vent pipes, and 17 and 27 are carbon dioxide gas bubbles.

When flocculating yeast is used as the microorganism in these conventional fermenters, the manner in which the yeast flocculate and the size of the yeast flocs generally depend on the fermentation conditions and the degree of disturbance of the reaction solution due to the generation of carbon dioxide gas. The small yeast flocs rise in the tank along with the generated carbon dioxide gas, and in the fermentation tank shown in FIG. However, in the case of the fermentation tank shown in Fig. 2, the superficial velocity of the gas is small, but in the case of the fermentation tank shown in Fig. 1, Since there is no part corresponding to the sedimentation separation section,
As expected, it was not possible to prevent the yeast floc from flowing out along with the fermentation liquid. In addition, in the case of fermentation using carrier-attached microbial cells, when trying to increase ethanol productivity, the amount of carrier-attached microbial cells flowing out of the tank also increased, although not as much as in the case of the flocculating yeast mentioned above. .

This invention was made in view of the above-mentioned circumstances, and it maintains a high concentration of microorganisms in the tank by keeping the superficial velocity of carbon dioxide low and preventing microorganisms from flowing out of the tank as much as possible. The purpose of the present invention is to provide a fermentation tank capable of improving the productivity of ethanol.

The fermentation tank according to the present invention is of a fluidized tank type for continuous fermentation, and as shown in FIG. A plurality of inclined body buttfuls 39 are arranged in a zigzag pattern at small intervals from each other, and horizontal guide plates 42 are provided at the small intervals between the body buttfuls 39. A head baffle 33 for sedimentation and separation of microorganisms is provided on the top.

The bottomed cylindrical tank body 31 may be cylindrical, or
A rectangular tubular shape may also be used. A raw material supply pipe 34 is arranged at the bottom of the fermentation tank, a fermentation liquid outflow pipe 35 is arranged at the front wall of the head 32, and a gas vent pipe 36 is arranged at the top wall.
are arranged.

The plurality of body buttfuls 39 include a rear buttful 4 which is inclined forwardly upward from the rear wall of the tank body 31.
0 and a front buttful 41 that is sloped backward upward from the front side wall of the tank body 31 are arranged in a zigzag shape and spaced apart from each other. The lower ends of the front and rear buffles 40 and 41 have a space between them and the side wall of the tank body 31 so that yeast floes and carrier-attached bacterial cells accumulated on the buffles fall downward. A horizontal guide plate 42 is interposed between the front side buttfuls 41, and a horizontal guide plate 42 is also provided below the lowest buttfull.
2 is placed. And these horizontal guides 4
2 is provided on the side wall of the tank body 31 in an inwardly protruding manner, and serves to guide gas bubbles along the body buffle 39.

The head buttfull 33 consists of a vertical part 33a and a sloped part 33b provided at the lower end of the vertical part 33a with a downward slope toward the front. It has a small spacing between it and the upper end of the sloping wall.

In the fermentation tank configured as described above, the fermentation liquid rises in a zigzag pattern along the body buffle 39 as shown by arrow A in FIG. In addition, a part of the fermentation liquid is transferred to each upper end of the body part full 39 and the horizontal guide plate 42.
By flowing through the gaps, a vortex is generated between the body buffles 39, as shown by arrow B. As a result, the superficial velocity of the carbon dioxide gas bubbles 37 generated by fermentation is suppressed to a low level, so that the amount of yeast flocs and microbial cells adhering to the carrier that rises with the air bubbles 37 is small, and even those that rise are absorbed by the head buff 33. Almost all of it settles and separates, and does not flow out of the tank.
In this way, the concentration of microorganisms in the tank is maintained high.

Next, in order to demonstrate the effects of the fermenter of the present invention, examples using the fermenter of the present invention and comparative examples using a conventional fermenter will be described.

Comparative Example 1 Using a fluidized tank type fermentation tank shown in Fig. 1, first, 5 wt/vol% of granular vermiculite with an average particle size of 0.4 mm was introduced into the tank as a carrier, and then microbial cells attached to the carrier were added. A preculture solution of Zymomonas mobilis ATCC-10988 was added at a concentration of 10 vol %, and batch culture was performed. Approximately 80 hours of culture solution, medium A below
and B were supplied into the tank at a ratio of A:B=1:9, and continuous fermentation was performed under the following fermentation conditions.

Medium A: Yeast extract 10g / (NH ₄ ) ₂ SO ₄ 10g / KH ₂ PO ₄ 10g / MgCl ₂・6H ₂ O 5g / MnCl ₂・4H ₂ O 40mg / ZnSO ₄・7H ₂ O 40mg / Antifoaming agent 3g / Medium B: Glucose 167 g / FeSO ₄ .7H ₂ O 33 mg / Fermentation conditions: Fermentation temperature 30°C PH 4.5 Ethanol productivity was examined by gradually increasing the supply amount of the medium, that is, gradually increasing the dilution rate. The results are shown in Figure 4. As is clear from the figure, ethanol productivity increased almost linearly up to a dilution rate of 0.3 h ^-1 , but at a dilution rate of 0.4 h ^-1 , the ethanol concentration decreased to approximately 50 g/ The weight did not increase above about 20 g/h. The cause of this was that the bacterial cells attached to the carrier flowed out of the tank.

Comparative Example 2 Using the fluidized tank type fermenter shown in Figure 1, first,
Batch culture was performed by adding a preculture solution of Saccharomyces uvarum IFO-2018 as a flocculating yeast to the tank at a concentration of 10 vol%. After culturing for about 80 hours, the following media C and D were supplied into the tank at a ratio of C:D=1:1.5,
Continuous fermentation was carried out under the following fermentation conditions.

Medium C: A mixture of 700 g of honey from the Philippines / 7 g of (NH ₄ ) ₂ SO ₄ / 0.5 g of K ₂ S ₂ O ₅ / 2.5 g of antifoaming agent and adjusted to PH4.5 with H ₂ SO ₄ . D: Tap water The relationship between dilution rate and ethanol productivity in this continuous fermentation is shown in Figure 5. As is clear from the figure, the ethanol productivity did not increase above about 7 g/h due to the outflow of flocculating yeast.

Comparative Example 3 The fermentation tank shown in Figure 2 was used as a fermentation tank (tank inner diameter = 80
The same operation as in Comparative Example 1 was repeated, except that the height was 4500 mm, the slope was 15° to the vertical, and the actual volume was approximately 20 mm.

Since the superficial velocity of the generated carbon dioxide gas was significantly reduced, the outflow of the bacterial cells attached to the carriers from the tank was prevented to some extent, but some outflow could not be avoided. Therefore, ethanol productivity did not increase above about 13 g/h.

Comparative Example 4 The same operations as in Comparative Example 2 were repeated, except that the fermenter used in Comparative Example 3 was used as the fermenter.

The sedimentation speed of flocculating yeast is as low as 0.3 to 0.4 m/sec, so the flow of yeast flocs out of the tank is significant.
Ethanol productivity remained at about 5 g/h.

Example 1 A plurality of body buttfuls and horizontal guide plates were provided inside the tank body of the fermentation tank used in Comparative Example 1.
The fermentation vessel shown in the figure was manufactured and the operations of Comparative Example 1 were repeated.

In the case of Comparative Example 1, as mentioned above, dilution rate =
At 0.4 h ^-1 , the ethanol concentration decreased and the ethanol productivity remained at about 20 g/h, but when multiple body buffs were provided as described above, ethanol concentration decreased even at a dilution rate of 0.5 h ^-1 . The concentration did not decrease, and the ethanol productivity reached approximately 35 g/h.

Example 2 Except for using the fermenter used in Example 1,
The operation of Comparative Example 2 was repeated.

In this case, the ethanol concentration does not decrease even at a dilution rate of 0.2 h ^-1 , and the alcohol productivity is approximately 14 g/
・It reached h.

As described above, according to the fermenter of this invention,
The inclined body buttfuls 39 of the tank body are arranged in a zigzag pattern at small intervals from each other, and each body part buttful 3
Since the horizontal guide plates 42 are provided at each of the small intervals between 9 and 9, it is possible to form a zigzag flow by the body part full 39, and a vortex can be formed by the horizontal guide plates 42. . Therefore, the superficial velocity of carbon dioxide gas generated during fermentation can be reduced, and as a result, yeast flocs and microbial cells attached to the carrier can be prevented from rising inside the tank due to carbon dioxide bubbles. can be suppressed to In addition, since a head baffle is provided in the head of the tank body, it is possible to sediment yeast flocs and carrier-adhered bacterial cells and maintain a high concentration of microorganisms in the tank. Productivity can be improved.

[Brief explanation of the drawing]

Figures 1 and 2 are vertical sectional views showing a conventional fermenter, Figure 3 is a vertical sectional view showing a fermenter according to the present invention, and Figures 4 and 5 are dilution ratios, ethanol concentrations, and productivity. It is a graph showing the relationship between 31...Tank body, 32...Head, 33...Head buttful, 38...Body, 39...Body buttful, 42...Horizontal guide plate.

Claims (1)

[Claims] 1 Inside the body 38 of the bottomed cylindrical tank body 31, a plurality of inclined body buttfuls 39 for reducing the superficial velocity of generated gas are arranged in a zigzag pattern at small intervals from each other. Horizontal guide plates 42 are provided at the small intervals between 39 and 39, respectively, and the head 3 of the tank body 31 is
A fermentation tank in which a head buttful 33 for sedimentation and separation of microorganisms is provided.